Sentence Correction

Unlike elite runners, whose times are calculated from the starter's pistol to the finish line, marathon times are calculated using a computer chip attached to each competitor's shoe.

a) Unlike elite runners, whose times are calculated from the starter's pistol to the finish line,
b) Besides elite runners, whose times are calculated from the starter's pistol to the finish line,
c) With the exception of elite runners, times for whom are calculated from the starter's pistol to the finish line,
d) Unless the runner is elite, in which case the time is calculated from the starter's pistol to the finish line,
e) With the exception being elite runners, whose times are calculated from the starter's pistol to the finish line,

OA: D

Source : Veritas Prep

Doubt: I don't clearly understand the reason behind the the right answer. Any thought?[/spoiler]

A direct comparision has to be made between times, reason being that "marathon times" follows the underlined part.
A, B, C and E are comparing elite runners with marathon times - illogical comparision

D)Unless the runner is elite {Till the time runner is elite} <-> marathon times - logical comparision - correct

IMO D

Thanks for the reply. Don't you think D makes the sentence a run-on sentence?